I printed them and posted my results here: Form 3 vs. Form 2 Faceoff!
TLDR: I got some layer shifting on the Form 3 as well.
I notice your most severe shifts are at layers where the supports contact the model, which could be telling. I know it’s not ideal, but you might be able to improve things by doubling the density of your supports. It could also be worth investigating other orientations (I know you tried a couple already).